Why do you think that a diesel engine will last longer? I am not an engineer, but I see no reason as to why the diesel engine will last longer than a gas engine. Diesels have a reputation for running up high mileages, but that is usually because they are purachased by those who travel a lot of miles, and therefore want low fuel consumption.

A diesel engine IS built more ruggedly, but because the compression ratio is more than twice that of a gasoline engine, I would think that the durability of both designs would be about equal.

I see posts on this board about 240 and 300 (617) engines having low compression and needing rebuilding all the time. When you have 70 or so HP pushing 3500lbs of auto around with 21:1 compression ration, the engine is going to be very stressed, no?

I would pick an m117 (450,560) gas(hog) against any diesel of the same era in a longevity comparison.

Mike